Wintering waterbird assemblages in the central part of the Gulf of Gabès in southern Tunisia

Although the Gulf of Gabès is recognised as an Important Bird Area, several aspects of the ecology of waterbirds inhabiting this area still need to be investigated. We observed how waterbird foraging guilds varied among habitats. In total, 49 species belonging to 16 families were recorded. Winter visitors accounted for 73% of counts. The avifauna was dominated by shorebirds (52% of records), followed by large wading birds (25%), open-water birds(18%) and waterfowl (5%). However, the structure of local waterbird communities and their composition in terms of foraging guilds varied according to habitat type. The bird communities of sandy beaches were dominated by open-water birds, whereas large mudflats were dominated by shorebirds, and wadi estuaries showed a more even representation of foraging guilds. Locally rare species had narrow distributions, whereas locally abundant species were found widely within the gulf. For four species the 1% population level criterion of the Ramsar Convention was exceeded. Overall, our results show that the Gulf of Gabès hosts important numbers of waterbirds with different ecological requirements, which confirms the importance of this gulf as a wintering area for Palearctic waterbirds.Keywords: abundance, foraging guilds, Gulf of Gabès, Tunisia, waterbird

Relationship between clutch size, egg volume and hatching success in a Yellow-legged Gull Larus michahellis colony in south-eastern Tunisia

This study aimed to test the hypothesis that clutch size covaries with egg volume and hatching success in the Yellow-legged Gull Larus michahellis. We determined clutch size and egg volume in a sample of 131 nests, and we used the data to check whether egg volume varied among nests according to clutch size, while taking into account the effects of egg laying order. We also estimated hatching success rate and investigated the relationship between hatching success and clutch size. Egg volume varied among clutches according to clutch size, with eggs being larger in three-egg clutches than in two-egg clutches. Moreover, three-egg clutches showed higher daily survival rates, and hence hatching success, than two-egg clutches. Overall, our results suggest that in the Yellow-legged Gull clutch size covaries with egg volume and hatching success, which could possibly reflect an age effect through different mechanisms. Indeed, older females could be hypothesised to exhibit greater breeding performance than younger females because of their higher  experience in tapping energy resources for egg formation and defending nests from dangers. Moreover, due to their age, older females are likely to have lower residual reproductive potential and should invest more heavily in current breeding attempts.Keywords: clutch size, egg volume, hatching success, Yellow-legged Gul

Exposure of resident sparrows to West Nile virus evidenced in South Tunisia

International audienceDuring the last few years, several cases of West Nile virus (WNV) infection in humans have been reported in Tunisia. However, detailed information on WNV infection in wild birds, the primary amplifying host of WNV, are lacking. In this work, we investigated the exposure of wild sparrows (hybrid Passer domesticus x hispaniolensis) living in two oases in southern Tunisia (Gabes and Kebili oases) to WNV, through the detection of WNV-specific antibodies by using ELISA and microneutralization tests. In total, 208 birds were sampled (54 from Kebili, 154 from Gabes). Anti-WNV antibodies were detected in two birds, corresponding to an overall seroprevalence of 1%. There was no significant difference between the two sampled populations [1.85% (1/54) in Kebili, 0.65% (1/154) in Gabes]. These data provide indirect evidence of the exposure of resident sparrows in southern Tunisia to WNV

Plurilinguisme, politique linguistique et éducation

Mayotte est une petite île française située dans l'océan Indien. Malgré son insularité, elle a toujours été ouverte aux apports étrangers ; sa situation géographique - à l'entrée du canal de Mozambique - l'expose à l'arrivée de tous ceux qui empruntent cette voie maritime sans obstacles. Historiquement, elle a des liens de proximité forts avec les autres îles de l'archipel des Comores et la grande île de Madagascar, ce qui explique la présence, sur son territoire, de deux langues locales, l'une d'origine bantoue, le shimaore, l'autre d'origine malgache, le kibushi. Celles-ci cohabitent avec la langue officielle et de la scolarisation : le français. Française depuis 1841, cette île est aujourd'hui exposée à une démographie galopante, une immigration massive et une mondialisation grandissante. Devenue le 101e département français depuis le 31 mars 2011, en pleine mutation socioculturelle, Mayotte doit faire face à tous ces obstacles. Les articles réunis dans cet ouvrage ne portent pas exclusivement sur Mayotte ; ils rendent compte aussi d'expériences et de travaux qui ont été menés dans d'autres pays ou dans des régions dont les situations linguistiques ressemblent à celle de Mayotte. Par la diversité de leurs regards et la richesse de leurs analyses, ces contributions apportent des éclairages importants sur la situation linguistique mahoraise et contribuent à approfondir le débat sur les rapports entre plurilinguisme, politique linguistique et éducation